The following discussion of the background of the invention is merely provided to aid the reader in understanding the invention and is not admitted to describe or constitute prior art to the present invention.
DNA profiling uses a variety of techniques to distinguish between individuals of the same species using only samples of their DNA. Two humans will have the vast majority of their DNA sequence in common. DNA profiling exploits highly variable repeating sequences called short tandem repeats (STRs). Two unrelated humans will be unlikely to have the same numbers of tandem repeats at a given locus. In STR profiling, PCR is used to obtain enough DNA to amplify the number of repeats at several loci. It is possible to establish a match that is extremely unlikely to have arisen by coincidence, except in the case of identical twins, who will have identical genetic profiles.
DNA profiling is used in forensic science, to match suspects to samples of blood, hair, saliva, semen, etc. It has also led to several exonerations of formerly convicted suspects. It is also used in such applications as identifying human remains, paternity testing, matching organ donors, studying populations of wild animals, and establishing the province or composition of foods. It has also been used to generate hypotheses on the pattern of the human diaspora in prehistoric times.
Testing is subject to the legal code of the jurisdiction in which it is performed. Usually the testing is voluntary, but it can be made compulsory by such instruments as a search warrant or court order. Several jurisdictions have also begun to assemble databases containing DNA information of convicts. The United States maintains the largest DNA database in the world: The Combined DNA Index System (CODIS), with over 4.5 million records as of 2007. The United Kingdom, maintains the National DNA Database (NDNAD), which is of similar size. The size of this database, and its rate of growth, is giving concern to civil liberties groups in the UK, where police have wide-ranging powers to take samples and retain them even in the event of acquittal.